The present invention relates generally to welding torches and, particularly, to a welding torch nipple for coupling a welding torch to a welding cable.
Several common metal welding techniques employ heat generated by electrical arcing to transition workpieces and/or filler metal to a molten state, for welding the workpieces together. One technique that employs this arcing principle is wire-feed welding. At its essence, wire-feed welding involves routing current from a power source and into a wire electrode that is brought into close proximity with the workpieces. When close enough, current arcs from the wire electrode to the workpieces, completing a circuit and generating sufficient heat to weld the workpieces to one another. Often, the wire electrode is consumed and becomes part of the weld itself. This technique is commonly referred to in the industry as gas metal arc welding (GMAW or MIG).
MIG welding traditionally requires the use of a welding torch to direct and route welding resources (e.g., electrical current, wire-electrode, shielding gas) toward the welding location. Specifically, such welding torches are connected to a welding cable that provides these resources, and include a neck assembly from which the welding resources egress toward the weld location. To couple the welding cable to the neck assembly, welding torches traditionally include a nipple that receives the welding cable and that routes these welding resources to the neck assembly.
Generally, such nipples are formed of two tubes: an inner tube disposed in an outer tube. The outer tube forms the outer shell of the nipple, and the inner tube engages with the welding cable to receive the welding resources. However, to protect a user from electrical shock, for instance, traditional nipples include a plastic layer disposed between the two tubes, thereby electrically isolating the outer tube from the inner tube.
Traditionally, this plastic layer is inserted between the two tubes by a press-fitting operation. Unfortunately, press-fitting operations often lead to bad alignment between the two tubes. That is, press-fitting often leads to misalignment between the central axes of the two tubes. Additionally, press-fitting can be a relatively taxing process, consuming valuable time and resources. Further still, press-fitting the plastic layer precludes a design in which a portion of the plastic layer extends radially beyond the smallest inner diameter of the outer tube. That is, the maximum outer diameter of the plastic layer can be no greater than the smallest inner diameter of the outer tube, because the plastic layer must be inserted axially into the outer tube. As a consequence, traditional nipple designs generally require the use of a plastic set-screw, which extends radially through the inner and outer tubes, to maintain electrical isolation between the two tubes when securing the neck assembly and nipple to one another. Unfortunately, plastic set-screws are generally not as durable as and are generally more expensive than metallic set-screws. Moreover, the lack of radial mechanical engagement between the plastic layer and the outer tube can, over time, lead to axial separation of the plastic layer and outer tube with respect to one another.
Therefore, there exists a need for improved nipples for welding torches.